1. Field of the Invention
The present invention relates to lighting systems that are digitally controlled and to the light fixtures used therein, and more particularly to such lighting systems as well as to multiparameter lights that have an image projection lighting parameter and a camera and that are useful in such lighting systems.
2. Description of the Related Art
Lighting systems are formed typically by interconnecting many light fixtures by a communications system and providing for operator control from a central controller. Such lighting systems may contain multiparameter light fixtures, which illustratively are light fixtures having individually remotely adjustable parameters such as beam size, color, shape, angle, and other light characteristics. Multiparameter light fixtures are widely used in lighting industry because they facilitate significant reductions in overall lighting system size and permit dynamic changes to the final lighting effect. Applications and events in which multiparameter light fixtures are used to great advantage include showrooms, television lighting, stage lighting, architectural lighting, live concerts, and theme parks. Illustrative multiparameter light devices are described in the product brochure entitled “The High End Systems Product Line 2001” and are available from High End Systems, Inc. of Austin, Tex.
Prior to the advent of relatively small commercial digital computers, remote control of light fixtures from a central controller was done with either a high voltage or low voltage current; see, e.g., U.S. Pat. No. 3,706,914, issued Dec. 19, 1972 to Van Buren, and U.S. Pat. No. 3,898,643, issued Aug. 5, 1975 to Ettlinger. With the widespread use of computers, digital serial communications over wire was widely adopted as a way to achieve remote control; see, e.g., U.S. Pat. No. 4,095,139, issued Jun. 13, 1978 to Symonds et al., and U.S. Pat. No. 4,697,227, issued Sep. 29, 1987 to Callahan. In 1986, the United States Institute of Theatre Technology (“USITT”) developed a digital communications system protocol for multi-parameter light fixtures known as DMX512. Basically, the DMX512 protocol consists of a stream of data which is communicated one-way from the control device to the light fixture using an Electronics Industry Association (“EIA”) standard for multipoint communications know as RS-485.
A variety of different types of multiparameter light fixtures are available. One type of advanced multiparameter light fixture which is referred to herein as an image projection lighting device (“IPLD”) uses a light valve to project images onto a stage or other projection surface. A light valve, which is also known as an image gate, is a device such as a digital micro-mirror (“DMD”) or a liquid crystal display (“LCD”) that forms the image that is projected. U.S. Pat. No. 6,057,958, issued May 2, 2000 to Hunt, discloses a pixel based gobo record control format for storing gobo images in the memory of a light fixture. The gobo images can be recalled and modified from commands sent by the control console. U.S. Pat. No. 5,829,868, issued Nov. 3, 1998 to Hutton, discloses storing video frames as cues locally in a lamp, and supplying them as directed to the image gate to produce animated and real-time imaging. A single frame can also be manipulated through processing to produce multiple variations. Alternatively, a video communication link can be employed to supply continuous video from a remote source.
U.S. Pat. No. 5,828,485, issued Oct. 27, 1998 to Hewlett, discloses the use of a camera with a DMD equipped light fixture for the purpose of following the shape of the performer and illuminating the performer using a shape that adaptively follows the performer's image. The camera taking the image preferably is located at the lamp illuminating the scene in order to avoid parallax. The image can be manually investigated at each lamp or downloaded to some central processor for this purpose. This results in a shadowless follow spot.